Multiple coil wound resistor



March 22, 1949. A. l.. LIVERA MULTIPLE COIL WOUND RESISTOR Filed April1945 Wh 7 j D, HM............

l N VEN TO R ldo ZI.- Z. wra/ ATTORNEYS Patented Mar. 22, 1949 MULTIPLECOIL WOUND RESISTOR Aldo L. Livera, Madison, N. J., assigner, by mesi-ieassignments, to John G. Ruckelshaus Company, a corporation of New JerseyApplication April 5, 1945, Serial No. 586,805

a claims. 1

This invention relates to coil wound elements, particularly to aninterconnected assembly of individual coil-wound impedance elements, andhas for an object to protect the interconnecting leads between saidindividual elements.

In the manufacture of multi-coil impedance elements having a pluralityof spools or coils which form integrated multi-ribbed spools, it hasbeen the practice in wiring the entire element to run the wire from oneterminal through a slot in a rib or flange forming a side of the spool,down the inner face of the ange, several turns being wound around a coreto secure the lead-in wire in position and then winding the requirednumber of turns on the core to form the usual coil. After the coil hasbeen completed in the rst spool, the wire is led through a. similar slotin the adjacent flange for the second spool and the above windingprocess is repeated, etc., until all spools have been wound, afterwhich'the end of the wire is secured to its corresponding terminal.

It has been found that opens often occur in impedance elementsmanufactured in the above manner, lparticularly when the element issubjected to wide ranges of temperature, as well as humidity, andinvestigation has revealed that the opens generally appear in the leadsinterconnecting the adjacent spools. The investigation further revealsthat the interconnecting leads upon completion of the winding operationare substantially taut even though suilicient slack in the wire wasprovided initially, the tautness of the wire being brought about by thefact that in winding a coil the various layers of wire contiguous to theinterconnecting lead force it against the face ofthe flange, therebytaking up the slack. Furthermore, a certain amount of abrasive action isproduced by the rubbing of the contiguous superposed coil wires againstthe interconnecting lead, so that the insulating medium therearound ispartially removed at the contact area thereof, thereby encouragingdeterioration, corrosion, and eventual breakage of the wire.

It is therefore another object of the invention to provide a simple andeconomical coil-wound impedance element free of the above manufacturingdefects.

It is still another object of the invention to provide an improvedcoil-wound impedance element in which suicient slack is assured for thelead-in and spool-interconnecting Wires.

It is a further object of the invention to lprovide an improvedcoil-wound impedance element substantially impervious to-huinidityconditions.

With the above objects in view, one embodiment of the inventiondiscloses a multi-spool coil form having a plurality of concatenatedcoils in which the lead-in and coil-interconnecting wires are assured apredetermined amount of slack by adhesively securing them to the innerspool flange surfaces, whereby these wires are also protected againstabrasive contact by the superposed layers of wire.

A more complete understanding of this invention will be obtained fromthe detailed description which follows and by reference to the a-ppendeddrawing in which:

Fig. 1 shows a perspective view of a multi-coil impedance element,

Fig. 2 shows an enlarged sectional View of the impedance element takenalong line 2-2 of Fig. 1, and

Fig. 3 shows a sectional view of one of the coil forms taken along line3 3 of Fig. 2.

Referring now to the drawing, particularly Figs. 1 and 2, there is shownan impedance element I0, such as a resistor of the multi-spool type,comprising a cylindrical core II with intermediate and outer flanges orwalls I2, I3, respectively, integral thereto for forming the core IIinto a series of interconnected spools within each of which a wire-Woundcoil I4 is contained. The core II. which may consist of any suitableinsulating material, such as Isolantite, may also be provided with anaxial bore I6 for equipment-mounting purposes. Each of the flanges I2and I3 is provided with aradial slot I'I, transversely therethrough, theseveral slots preferably being in alignment. Radial slots I'I areprovided in the inner flanges I2 for passage therethrough of Ithecoil-interconnecting leads I8 while the radial slots II in the end angesI3 are provided for the lead-in wires I9, which are connected toterminals 2| in aimanner to be described hereinafter.

In manufacturing the impedance element in accordance with the invention,let it be assumed that the wiring, which may be insulated by any of thewell-known insulating mediums, such as enamel, is initiated from theleft side of the unit,

as viewed in Fig. 2. The lead-in wire I9 is ilrst connected to terminal2| by the usual soldered collar 20 which, briefly, comprises windingseveral turns of the lead-in wire in a recess 22 formed in the core andapplying a collar of solder thereto, whereby the terminal 2| and turnsof wire I9, which ypreferably are rst tinned tc facilitate the solderingoperation, are electrically and mechanically interconnected. The lead-inwire I9 is then passed through slot I1 of flange I3 and down the innerface thereof to the peripheral surface of core II. As shown in Fig. 2,the lead-in wire I9 is provided with a certain amount of slack, which isdisposed within the slot I1. A few turns of the wire are then woundaround the core a small distance away from the face of flange I3 tosecure the wire in place, and the wire is then pushed back against theflange face to provide additional slack for the wire I9.

The next step comprises fastening the wire I9 to the side wall of theange I3 by any suitable adhesive material, such as acetate tape 23, in amanner shown particularly in Figs. 2 and 3, the bulge of wire I9 in theslot I1 evidencing the approximate amount of slack. It can be readilyseen that the adhesive tape 23 insures slack in the lead-in wire I9 andat the same time provides an additional insulating cover for the wirewhich is, therefore, protected from abrasions as the remaining turns ofwire for the coil Il are wound on the core I I. The required number ofturns are then wound around the core II and the interconnecting lead I8from the flrst coil I4 is then passed through the slot I1 formed in theadjacent inner flange I2, and the procedure of securing the wire I8 bytape 23 is repeated to provide the reuuired amount of slack. It will benoted here that the adhesive tape 23 after being secured to the face 'ofyflange I2 is continued over the peripheral outer edge of flange I2,over the slot I1 formed therein, partially down the other face of theflange I2 and across to the adjacent flange IT, where it is adhesivelysecured to the top of the previously-secured tape 23. The above windingprocess is repeated for the remainder of the individual spools, afterwhich the lead-in wire I9 for the extreme right spool I4. as viewed inFig. 2, is connected to its terminal 2| in a similar manner to that atwhich the left lead-in wire I9 was connectedl to its terminal 2|. Thusan impedance element comprising a series of interconnected coil windingsis formed. The terminals 2| provide a suitable means for electricallyconnecting the impedance I to an external circuit not shown).

The final step in the manufacturing process comprises dipping theimpedance element I0 into any of the well-known impregnating materials,whereby the element I0 is further fortified against insulationresistance breakdown. By placing the tape 23 o ver the slots I1, asdescribed hereinbefore, it has been found that the impregnated materialremains within the slots after the dipping operation. process theimpregnatingmaterial did not adequately cover the wires I8, I9 in theslots I1, having dropped out of said slots I1 when the impedance elementwas removed from the impregnating compound. It is thus seen by virtue ofthe addition of the above tape 23 that a further advantage accrues tothe manufacture of animproved impedance element I0 in accordance withthis invention, namely, greater protection from an insulation resistancestandpoint being provided for the interconnected and lead-in Wires Inthe prior manufacturing' I8, I9, respectively, whereby the impedanceelement I0 may be employed under situations where wide ranges intemperature and humidity are encountered.

While this invention has been shown and described as embodying certainfeatures merely for the purpose of illustration, it is clear to anyoneskilled in the art that many modifications are possible withoutdeparting from the spirit of the invention and the scope of the appendedclaims.

For example, while the invention has been described in connection with amulti-coil wound structure, it is, of course, to be understood that theinvention may also be applied to a single coil wound impedance element.

Additionally, and also by way of example, it will be obvious to thoseskilled in the art that the advantages of the insulated tape asdescribed above are equally applicable to resistors in which the flangebetween spools is not slotted, but, for example, ilattened or notched,and the lead from one spool to the other passes up, over, and down theflange sides. y

What is claimed is: v

1. An impregnated impedance element comprising an insulating core, aplurality of spaced radially-extending flanges integrally formed on saidcore, each of said flanges having a radial slot therein, a plurality ofturns of wire wound on said core to form individual coils betweenadjacent flanges, said coils lbeing interconnected serially and beingterminated in a pair of lead-in wires, said interconnecting and lead-inwires being extended through respective ones of said slots, a pair ofterminals connected to said leadin wires, and an adhesive insulatingtape adherently applied to each flange over each lead-in wire so as tocover said wire and secure it to the side face of the associated flange,whereby a predetermined amount of slack is 'provided for said wires insaid slots, each insulating tape also being disposed over the slot inthe associated flange for preventing loss of impregnating material fromthe slot, extended across to the next adjacent flange and adherentlysecured to the tape on said flange.

2. The method of manufacturing an electrical impedance element of thewired-spool type having at least a pair of flanges and a radial slot ineach of said flanges which comprises securing a wire tofone end of thespool, passing the wire through one of the slots, securing the wire tothe associated flange with a predetermined amount of slack providedwithin the slot by covering the slot and that portion of the wireextending therefrom along the flange with an adhesive element, winding apredetermined number of turns of wire around the spool, thereafterpassing the wire through the slot of the other ilange and securing thewire to the other end of the spool.

3. The method of manufacturing electrical impedance elements of thewired-spool type having a core and at least a pair of flanges with aradial slot in each of said flanges which comprises securing a wire toone end of the spool, passing the wire through the slot in one of theflanges, extending the wire to the core at an angle to the flange,winding at least two turns around the core adjacent said flange, pushingthese turns against the face of the flange to provide slack in the vwirein the slot, securing the Wire to the flange by applying adhesive tapethereto, covering the slot with the same portion of tape, thereafterwinding a predetermined number of turns of wire upon the core, extendingthe wire through the slot of the other nange, and securing the wire tothe other end of the spool.

ALDO L. LIVERA. REFERENCES CITED 6 The following references are ofrecord in the i'lle of this patent:

UNITED STATES PATENTS Number Name Date 10 1,976,514 Pugh Oct. 9, 19342,047,798 Ogg July 14, 1930 2,286,161 Rights et ai June 9. 1942 neming tJohnson. Insulation and Design of Electrical windings, 1913.

Brunner. "Armature Winding and Motor Repair, 1920.

